US5931128A - Variable valve mechanism and internal combustion engine with the same - Google Patents
Variable valve mechanism and internal combustion engine with the same Download PDFInfo
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- US5931128A US5931128A US09/010,623 US1062398A US5931128A US 5931128 A US5931128 A US 5931128A US 1062398 A US1062398 A US 1062398A US 5931128 A US5931128 A US 5931128A
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- axis
- rotation axis
- supporting member
- rotation
- supporting
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
- F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/02—Valve drive
- F01L1/024—Belt drive
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
- F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
- F01L1/356—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear making the angular relationship oscillate, e.g. non-homokinetic drive
Definitions
- This invention relates to a variable valve mechanism which opens and closes intake and/or exhaust valve(s) of an internal combustion engine at a timing corresponding to an operation state of the engine and an internal combustion engine equipped with such a variable valve mechanism and, in particular, to a variable valve mechanism utilizing a nonuniform coupling which can increase or decrease, during one rotation, the rotational speed inputted therein and output thus changed rotational speed and an internal combustion engine equipped with such a variable valve mechanism.
- a reciprocating internal combustion engine (hereinafter referred to as engine) is equipped with intake and exhaust valves (which are hereinafter collectively referred to as engine valves or simply as valves). Since such a valve is driven in a valve lift state corresponding to the form of a cam or its rotational phase, the opening/closing timing of the valve and the opening period thereof (quantity, by unit of rotational angle of a crank, indicating a period in which the valve is open) also corresponds to the form of the cam or its rotational phase.
- variable valve timing apparatus variable valve mechanisms which can alter the opening/closing timing and opening period of such a valve.
- a nonuniform coupling employing an eccentric mechanism is inserted between a cam and a camshaft, whereas the camside rotation axis is set at a position eccentric to the camshaft-side rotation axis, and the eccentric state of the cam-side rotation axis in the eccentric mechanism (i.e., axial center position of the camshaft-side rotation axis) is adjusted so that, while the camshaft makes one rotation, the cam increases or decreases its rotational speed or changes its phase, thus allowing the opening/closing timing and opening period of the valve to be regulated.
- a turning force is transmitted to the cam via the nonuniform coupling.
- such turning force is transmitted through complex transmission paths between the camshaft-side rotating member and the cam-side rotating member that rotate with rotating axial centers eccentric to each other in the nonuniform coupling by way of several kinds of members such as connecting members (e.g., pin elements) which transmit the turning force while radially sliding.
- a member (axis-supporting member) for holding the cam-side rotation axis in a predetermined eccentric state with respect to the camshaft-side rotation axis is necessary.
- this axis-supporting member is required to change its position so as to alter the eccentric state (position of the eccentric axial center in general) of the cam-side rotation axis relative to the camshaft-side rotation axis.
- an axis-supporting member rotates or swings within a predetermined range upon adjustment of the opening/closing timing and opening period of the valve, it is basically a member on the fixed side and does not rotate together with the cam-side rotation axis or camshaft-side rotation axis. Namely, the axis-supporting member bears the above-mentioned large friction at least at its sliding surface with respect to the cam-side rotation axis.
- Such friction is deemed to greatly influence, when the axis-supporting member is rotated or swung in order to adjust the valve characteristics (opening/closing timing and opening period), the response of the axis-supporting member and an actuator for rotating or swinging the axis-supporting member.
- variable valve mechanism utilizing a nonuniform coupling equipped with a member (axis-supporting member) for supporting a cam-side rotation axis in an eccentric state, in which, when driving the axis-supporting member, its driving is effected while the friction occurring between the cam-side rotation axis and the axial supporting member is taken into account, thus making it possible to attain improvement in the response of the axis-supporting member to and alleviation in burden on an actuator for the axis-supporting member; and an internal combustion engine equipped with the variable valve mechanism.
- a variable valve mechanism in accordance with the present invention comprises a first rotation axis member driven to rotate around a first rotation axis center in response to a turning force transmitted from a crankshaft of an internal combustion engine; an axis-supporting member equipped with an axis-supporting section having a second rotation axis center which is different from and in parallel to the first axis center, the axis-supporting member being disposed around an outer periphery of the first rotation axis member so as to be able to rotate or swing relative thereto such that the second rotation axis center can be displaced; an intermediate rotating member axially supported by the axis-supporting member; a first connecting member linking the intermediate rotating member to the first rotation axis member so that the intermediate rotating member can rotate together with the first rotation axis member; a second rotation axis member which rotates around the first rotation axis center and has a cam section; a second connecting member linking the second rotation axis member to the intermediate rotating member so that the second rotation axis
- a variable valve mechanism in accordance with the present invention comprises a first rotation axis member driven to rotate around a first rotation axis center in response to a turning force transmitted from a crankshaft of an internal combustion engine; an axis-supporting member equipped with an axis-supporting section having a second rotation axis center which is different from and in parallel to the first axis center, the axis-supporting member being disposed around an outer periphery of the first rotation axis member so as to be able to rotate or swing relative thereto such that the second rotation axis center can be displaced; an intermediate rotating member axially supported by the axis-supporting member; a first connecting member linking the intermediate rotating member to the first rotation axis member so that the intermediate rotating member can rotate together with the first rotation axis member; a second rotation axis member which rotates around the first rotation axis center and has a cam section; a second connecting member linking the second rotation axis member to the intermediate rotating member so that the second rotation axis
- An internal combustion engine equipped with a variable valve mechanism in accordance with the present invention is an internal combustion engine in which variable valve mechanisms are respectively disposed on intake and exhaust sides thereof, each of the variable valve mechanisms comprising a first rotation axis member driven to rotate around a first rotation axis center in response to a turning force transmitted from a crankshaft of the internal combustion engine; an axis-supporting member equipped with an axis-supporting section having a second rotation axis center which is different from and in parallel to the first axis center, the axis-supporting member being disposed around an outer periphery of the first rotation axis member so as to be able to rotate or swing relative thereto such that the second rotation axis center can be displaced; an intermediate rotating member axially supported by the axis-supporting member; a first connecting member linking the intermediate rotating member to the first rotation axis member so that the intermediate rotating member can rotate together with the first rotation axis member; a second rotation axis member which rotates around the first rotation axis
- an internal combustion engine equipped with a variable valve mechanism in accordance with the present invention is an internal combustion engine in which variable valve mechanisms are respectively disposed on intake and exhaust sides thereof, each of the variable valve mechanisms comprising a first rotation axis member driven to rotate around a first rotation axis center in response to a turning force transmitted from a crankshaft of the internal combustion engine; an axis-supporting member equipped with an axis-supporting section having a second rotation axis center which is different from and in parallel to the first axis center, the axis-supporting member being disposed around an outer periphery of the first rotation axis member so as to be able to rotate or swing relative thereto such that the second rotation axis center can be displaced; an intermediate rotating member axially supported by the axis-supporting member; a first connecting member linking the intermediate rotating member to the first rotation axis member so that the intermediate rotating member can rotate together with the first rotation axis member; a second rotation axis member which rotates around the first rotation axis
- FIGS. 1(A) and 1(B) are schematic sectional views for explaining operation settings for main parts of nonuniform couplings in a variable valve mechanism in accordance with a first embodiment of the present invention, respectively showing the one installed on the intake valve side and the one installed on the exhaust valve side;
- FIG. 2 is a perspective view of the variable valve mechanism in accordance with the first embodiment of the present invention.
- FIG. 3 is a sectional view showing main parts of the variable valve mechanism in accordance with the first embodiment of the present invention
- FIG. 4 is a schematic sectional view showing an arrangement of main parts of the nonuniform coupling in the variable valve mechanism in accordance with the first embodiment of the present invention
- FIG. 5 is a sectional view, taken along line B--B in FIG. 3, showing the nonuniform coupling in the variable valve mechanism in accordance with the first embodiment of the present invention
- FIG. 6 is a sectional view, taken along line A--A in FIG. 3, showing the nonuniform coupling in the variable valve mechanism in accordance with the first embodiment of the present invention
- FIGS. 7(A1) to 7(A3) and FIGS. 7(B1) to 7(B3) are views showing operation principles of the nonuniform speed mechanism in the variable valve mechanism in accordance with the first embodiment of the present invention, wherein FIGS. 7(A1) to 7(A3) show relationships between rotational phases of a first rotation axis member (camshaft) and an intermediate rotating member (engagement disc), whereas FIGS. 7(B1) to 7(B3) show relationships between rotational phases of the intermediate rotating member (engagement disc) and a second rotation axis member (cam lobe);
- FIGS. 8(a1) to 8(a5), FIGS. 8(b1) to 8(b5), and 8(c) are characteristic views for explaining operation characteristics of the nonuniform speed mechanisms in the variable valve mechanism in accordance with the first embodiment of the present invention, wherein FIGS. 8(a1) to 8(a5) indicate operation states at a high speed, FIGS. 8(b1) to 8(b5) indicate operation states at a low speed, and FIG. 8(c) is a graph for explaining an angle of rotational phase of the second rotation axis member (cam lobe);
- FIG. 9 is an exploded perspective view of the variable valve means in accordance with the first embodiment of the present invention.
- FIG. 10 is a view showing a power-transmitting path for adjusting an eccentric position of the variable valve mechanism in accordance with the first embodiment of the present invention
- FIG. 11 is a view showing an actuator of an eccentric position adjusting mechanism in the variable valve mechanism in accordance with the first embodiment of the present invention.
- FIG. 12 is a view for explaining a nonuniform speed mechanism in the variable valve mechanism in the first embodiment of the present invention, showing examples of changes in valve lift amount, valve moving speed, and valve moving acceleration in the engine;
- FIG. 13 is a view for explaining a setting for the nonuniform speed mechanism of the variable valve mechanism in the first embodiment of the present invention, illustrating a force applied to the intermediate rotating member (engagement disc);
- FIG. 14 is a view for explaining a setting for the nonuniform speed mechanism of the variable valve mechanism in the first embodiment of the present invention, illustrating vectors of the force applied to the intermediate rotating member (engagement disc) in response to the phase of a cam;
- FIGS. 15(A) and 15(B) are views for explaining settings of the nonuniform speed mechanism in the variable valve mechanism in the first embodiment of the present invention, respectively illustrating vectors of forces applied to the intermediate rotating member (engagement disc) in response to the phase of cam in a low speed region and a high speed region;
- FIG. 16 is a view for explaining a setting of the nonuniform speed mechanism in the variable valve mechanism in the first embodiment of the present invention, showing the torque required for driving the cam in relation to camshaft angle in the case where the engine is in its low speed region;
- FIG. 17 is a view for explaining a setting of the nonuniform speed mechanism in the variable valve mechanism in the first embodiment of the present invention, showing the torque required for driving the cam in relation to camshaft angle in the case where the engine is in its high speed region;
- FIGS. 18(A) and 18(B) are schematic sectional views for explaining operation settings of main parts of nonuniform couplings in the variable valve mechanism in accordance with a second embodiment of the present invention, respectively illustrating the one installed on the intake side and the one installed on the exhaust side;
- FIG. 19 is a characteristic view for explaining an effect of the operation setting in the variable valve mechanism in accordance with the second embodiment of the present invention.
- FIGS. 20(A) and 20(B) are schematic sectional views for explaining operation settings of main parts of nonuniform couplings in the variable valve mechanism in accordance with a third embodiment of the present invention, respectively illustrating the one installed on the intake side and the one installed on the exhaust side;
- FIGS. 21(A) and 21(B) are schematic sectional views for explaining operation settings of main parts of nonuniform couplings in the variable valve mechanism in accordance with a fourth embodiment of the present invention, respectively illustrating the one installed on the intake side and the one installed on the exhaust side.
- FIGS. 1 to 17 show a variable valve mechanism and an internal combustion engine equipped with the variable valve mechanism in accordance with a first embodiment of the present invention
- FIGS. 18 and 19 show the variable valve mechanism in accordance with a second embodiment of the present invention
- FIG. 20 shows the variable valve mechanism in accordance with a third embodiment of the present invention
- FIG. 21 shows the variable valve mechanism in accordance with a fourth embodiment of the present invention.
- the internal combustion engine in accordance with this embodiment is a reciprocating internal combustion engine, and the variable valve mechanism in accordance with this embodiment is disposed so as to drive an intake valve or exhaust valve (collectively referred to as engine valve or simply as valve) placed above a cylinder.
- intake valve or exhaust valve collectively referred to as engine valve or simply as valve
- FIGS. 2, 3, and 4 are respectively a perspective view, a sectional view, and a schematic configurational view (schematic view observed from an axial end face) each showing main parts of the variable valve mechanism.
- a cylinder head 1 is equipped with a valve (valve member) 2 for opening and closing an intake port or exhaust port which is not depicted.
- a stem end portion 2A of the valve 2 is provided with a valve spring 3 (see FIG. 4) for biasing the valve 2 toward its closing side.
- a rocker arm 8 abuts to the stem end portion 2A of the valve 2
- a cam 6 abuts to the rocker arm 8.
- a protruded portion (cam crest portion) 6A of the cam 6 drives the valve 2 toward its opening direction against the bias force of the valve spring 3.
- the variable valve mechanism is provided in order to pivot such cam 6.
- variable valve mechanism comprises a cam shaft (first rotation axis member) 11 which is driven to rotate together with a crankshaft (not depicted) of the engine via belt (timing belt) 41 and a pulley 42, and a cam lobe (second rotation axis member) 12 disposed around the outer periphery of the camshaft 11, the cam (cam section) 6 projects from the outer periphery of the cam lobe 12.
- the outer periphery of the cam lobe 12 is axially supported in a rotatable fashion by a bearing section 7 on the cylinder head 1 side.
- the camshaft 11 is supported by the bearing section 7 via the cam lobe 12, while an end portion of the camshaft 11 is axially supported by a bearing section 1A of the cylinder head 1 via an end member 43 connected onto the same axial line. Since the pulley 42 is attached to such end member 43, the latter incorporating the pulley 42 can be referred to as an input section.
- the bearing section 7 which is configured so as to be separable into two parts, comprises a bearing lower half 7A formed in the cylinder head 1, a bearing cap 7B joining the bearing lower half 7A from thereabove, and a bolt 7C for connecting the bearing cap 7B to the bearing lower half 7A.
- a joining surface 7D between the bearing lower half 7A and the bearing cap 7B is set substantially horizontal so as to become orthogonal to the non-depicted axial line of the cylinder, whereby the bolt 7C fastened substantially in the vertical direction (upward/downward direction) in FIGS. 3 and 4 firmly connects the bearing lower half 7A and the bearing cap 7B together in the vertical direction.
- This variable valve mechanism is suitable for a multi-cylinder engine.
- the cam lobe 12 and the nonuniform coupling 13 are provided for each cylinder.
- the variable valve mechanism is applied to a straight four-cylinder engine.
- the nonuniform coupling 13 comprises a control disc (axis-supporting member) 14 pivotally supported by the outer periphery of the camshaft 11; an eccentric section (axis-supporting section) 15 integrally formed with the control disc 14; an engagement disc (intermediate rotating member) 16 disposed around the outer periphery of the eccentric section 15; and a first slider member (first connecting member) 17 and a second slider member (second connecting member) 18 which are connected to the engagement disc 16.
- the eccentric section 15 has a rotation center O 2 at a position eccentric to a rotation center (first rotation center axis line) O 1 of the camshaft 11, and the engagement disc 16 rotates around the center (second rotation center axis line) O 2 of the eccentric section 15.
- the first slider member 17 and the second slider member 18 respectively have slider main sections 21 and 22 at their tip portions, and drive pin sections 23 and 24 on the other end side.
- one surface of the engagement disc 16 is radially formed with a slider groove 16A in which the slider main section 21 of the first slider member 17 is slidably fitted, and a slider groove 16B in which the slider main section 22 of the second slider member 18 is slidably fitted.
- the two slider grooves 16A and 16B are disposed on the same diameter such that their phases of rotation shift from each other by 180°.
- the camshaft 11 is provided with a drive arm 19; the cam lobe 12 is provided with an arm section 20; the drive arm 19 has a hole section 19A into which the drive pin section 23 of the first slider member 17 is rotatably fitted; and the arm section 20 has a hole section 20A into which the drive pin section 24 of the second slider member 18 is rotatably fitted.
- the drive arm 19 is disposed so as to radially project from the camshaft 11 and is connected by a lock pin 25 to the camshaft 11 so as to rotate together therewith.
- the arm section 20 is integrally formed with the cam lobe 12 so that the end portion of the latter radially and axially projects to a position approximating one side face of the engagement disc 16.
- a turning force is transmitted between outer planes 21B, 21C of the slider main section 21 and inner wall planes 28A, 28B of the groove 16A between the slider main section 21 and the groove 16A; whereas a turning force is transmitted between inner wall planes 28C, 28D of the groove 16B and outer planes 22B, 22C of the slider main section 22 between the groove 16B and the slider main section 22.
- FIGS. 7(A1) to 7(A3) and FIGS. 7(B1) to 7(B3) are views illustrating that the cam lobe 12 rotates at a speed different from the camshaft 11, wherein FIGS. 7(A1) to 7(A3) show a change in rotational speed of the engagement disc 16 relative to the camshaft 11, whereas FIGS. 7(B1) to 7(B3) show a change in rotational speed of the cam lobe 12 relative to the engagement disc 16.
- S1 indicates the position of a reference point on the camshaft 11 side (e.g., center point of the first slider member 17) in the rotation reference position
- H1 indicates a reference point on the engagement disc 16 side (e.g., reference point of the slider groove 16A) in the rotation reference position.
- S2 to S12 respectively indicate positions attained when the reference point on the camshaft 11 side (center point of the first slider member 17) is rotated by increments of a predetermined angle (30° here), whereas H2 to H12 respectively show points of the reference point on the engagement disc 16 side (reference point of the slider groove 16A) rotating in response to the reference point positions S2 to S12 on the camshaft 11 side.
- the reference point on the camshaft 11 side is rotated around the first rotation center axis line O 1
- the reference point on the engagement disc 16 side is rotated around the second rotation center axis line O 2 .
- the engagement disc 16 side rotates from H6 to H7 by an angle of ⁇ H6 ⁇ O 2 ⁇ H7, whereby it rotates by a rotational angle smaller than that on the camshaft 11 side ( ⁇ H6 ⁇ O 2 ⁇ H7 ⁇ S6 ⁇ O 1 ⁇ S7) here. Namely, during this period, the engagement disc 16 side rotates at a lower speed than the camshaft 11 side.
- the engagement disc 16 side rotates at the highest speed at the position H1 relative to the camshaft 11 side; and then, while the camshaft 11 side successively rotates from S1 to S2, S3, S4, S5, S6, and S7, the cam disc 16 side gradually reduces its speed relative to the camshaft 11 side as it successively rotates from H1 to H2, H3, H4, H5, H6, and H7.
- the engagement disc 16 side attains a speed substantially the same as that of the camshaft 11 side in the proximity of the region between points H3 to H5, and thereafter the engagement disc 16 side becomes slower than the camshaft 11 side, while rotating at the lowest speed at the position H7 relative to the camshaft 11 side.
- the cam disc 16 side gradually increases its speed relative to the camshaft 11 side as it successively rotates from H7 to H8, H9, H10, H11, H12, and H1.
- the engagement disc 16 side attains a speed substantially the same as that of the camshaft 11 side in the proximity of the region between points H9 and H10, and thereafter the engagement disc 16 side becomes faster than the camshaft 11 side, while rotating at the highest speed at the position H1 relative to the camshaft 11 side.
- FIG. 7(A3) shows the rotational speed on the engagement disc 16 side relative to that on the camshaft 11 side according to the rotational angle of the camshaft 11 (assumed to rotate clockwise with the position S1 being set to 0° or 360°).
- the rotational speed of the camshaft 11 is set constant (on abscissa), and the rotational speed on the engagement disc 16 side changes with a characteristic similar to a cosine curve.
- FIGS. 7(B1) to 7(B3) With respect to such rotation on the engagement disc 16 side, the rotational speed on the cam lobe 12 side changes as shown in FIGS. 7(B1) to 7(B3).
- FIGS. 7(A1) to 7(A3) respectively correspond to FIGS. 7(B1) to 7(B3).
- H'1 indicates the position of a reference point on the engagement disc 16 side (e.g., reference point of the slider groove 16B) in the rotation reference position
- R1 indicates a reference point on the cam lobe 12 side (e.g., center point of the second slider member 18) in the rotation reference position.
- H'2 to H'12 indicate second reference points (reference points of the slider groove 16B) on the engagement disc 16 side respectively corresponding to the first reference points (reference points of the slider groove 16A) H2 to H12 on the engagement disc 16 side
- R2 to R12 respectively show positions of the reference point on the cam lobe 12 side (center point of the second slider member 18) rotated in response to the second reference points (reference points of the slider groove 16B) H'2 to H'12 on the engagement disc 16 side.
- the reference point on the engagement disc 16 side is rotated around the second rotation center axis line O 2
- the reference point on the cam lobe 12 side is rotated around the first rotation center axis line O 1
- the cam lobe 12 side rotates with a characteristic in which the speed characteristic on the engagement disc 16 side relative to the camshaft 11 side is further enhanced.
- the cam lobe 12 side rotates at the highest speed at the position R1 relative to the engagement disc 16 side; and thereafter, while the engagement disc 16 side successively rotates from H'1 to H'2, H'3, H'4, H'5, H'6, and H'7, the cam lobe 12 side gradually reduces its speed relative to the engagement disc 16 side while successively rotating from R1 to R2, R3, R4, R5, R6, and R7.
- the cam lobe 12 side attains substantially the same speed as the engagement disc 16 side in the proximity of the region between the positions R3 and R4, and thereafter the cam lobe 12 side becomes slower than the engagement disc 16 side, while rotating at the lowest speed at the position R7 relative to the engagement disc 16 side.
- the cam lobe 12 side gradually increases its speed relative to the engagement disc 16 side while successively rotating from R7 to R8, R9, R10, R11, R12, and R1. During this period, the cam lobe 12 side attains substantially the same speed as the engagement disc 16 side in the proximity of the region between the positions R9 and R10, and thereafter the cam lobe 12 side becomes faster than the engagement disc 16 side, while rotating at the highest speed at the position R1 relative to the engagement disc 16 side.
- FIG. 7(B3) indicates such a rotational speed characteristic on the cam lobe 12 side in response to the rotational speed characteristic on the engagement disc 16 side characteristic similar to that shown in FIG. 7(A3)!.
- the rotational speed on the cam lobe 12 side changes with a cosine-curve-like characteristic similar to the rotational speed on the engagement disc 16 side, while the characteristic on the engagement disc 16 side is further enhanced (i.e., amplitude is enhanced).
- the rotational speed on the cam lobe 12 side changes with a characteristic similar to a cosine curve.
- the rotational phase characteristic on the cam lobe 12 side corresponding to the rotational angle of the camshaft 11 thereafter, i.e., the advancing or retarding characteristic of the rotational phase on the cam lobe 12 side relative to the rotational phase of the camshaft 11 side corresponds to the value obtained when the rotational speed on the cam lobe 12 side relative to the rotational speed on the camshaft 11 side see FIG. 7(B3)! is integrated.
- the cam lobe 12 side retards from the camshaft 11 side, while gradually increasing its retarding angle.
- the cam lobe 12 side retards farthest relative to the camshaft 11 side see FIG. 8(a4)!.
- the cam lobe 12 side retards from the camshaft 11 side, its retarding angle gradually decreases.
- the cam lobe 12 side attains the same phase angle as the camshaft 11 side see FIG. 8(a5)!.
- valve lift curve VL1 in FIG. 8(c) indicates the lift curve characteristic (lift curve base) in the case where the cam lobe 12 side is not eccentric to the cam shaft 11 side, whereby the cam lobe 12 side always attains the same constant phase angle as that of the cam lobe 12 side.
- valve opening timing (opening starting time) ST1 becomes earlier than opening timing STO of the lift curve base
- valve closing timing (opening ending time) ET1 becomes later than closing timing ETO of the lift curve base.
- the valve opening timing ST1 becomes earlier than that in the lift curve base since the rotational phase angle on the cam lobe 12 side is advanced from that on the camshaft 11 side in the region where the valve starts its opening.
- the valve closing timing ET1 becomes later than that of the lift curve base since the rotational phase angle on the cam lobe 12 side is retarded from that on the camshaft 11 side in the region where the valve terminates its opening.
- the cam lobe 12 side attains the same phase angle as that on the camshaft 11 side when the camshaft rotational angle is zero as shown in FIG. 8(a1). Thereafter, as the camshaft 11 pivots from 0° to 90°, the cam lobe 12 side retards from the camshaft 11 side, while gradually increasing its retarding angle. When the camshaft 11 becomes 90°, the cam lobe 12 side retards farthest from the camshaft 11 side see FIG. 8(b2)!. Thereafter, while the camshaft 11 pivots from 90° to 180°, though the cam lobe 12 side is retarded from the camshaft 11 side, its retarding angle gradually decreases. When the camshaft 11 becomes 180°, the cam lobe 12 side attains the same phase angle as that on the camshaft 11 side see FIG. 8(b3)!.
- the cam lobe 12 side advances from the camshaft 11 side, while gradually increasing its advancing angle.
- the cam lobe 12 side advances farthest from the camshaft 11 side see FIG. 8(b4)!.
- the camshaft pivots from 270° to 360°, though the cam lobe 12 side advances from the camshaft 11 side, its advancing angle gradually decreases.
- the cam lobe 12 side attains the same phase angle as that on the camshaft 11 side see FIG. 8(b5)!.
- valve opening timing (opening starting time) ST2 becomes later than the opening timing STO of the lift curve base
- valve closing timing (opening ending time) ET2 becomes earlier than the closing timing ETO of the lift curve base
- valve opening timing ST2 becomes earlier than that in the lift curve base since the rotational phase angle on the cam lobe 12 side is retarded from that on the camshaft 11 side in the region where the valve starts its opening.
- valve closing timing ET2 becomes earlier than that of the lift curve base since the rotational phase angle on the cam lobe 12 side is advanced from that on the camshaft 11 side in the region where the valve terminates its opening.
- the valve lift curve characteristic can be changed in response to the rotation center (second rotation center axis line) O 2 of the engagement disc 16, i.e., eccentric position of the engagement disc 16.
- the valve opening period is elongated so as to become suitable for the high-speed rotation of the engine.
- the valve opening period is shortened so as to become suitable for the low-speed rotation of the engine.
- valve 2 When the rotation center (second rotation center axis line) O 2 of the engagement disc 16 is located at an intermediate position between the positions shown in FIGS. 8(a1) and 8(b1), the valve 2 is driven with a valve characteristic (valve opening timing and closing timing) corresponding to this position.
- the valve characteristic approaches the lift curve base characteristic represented by curve VL0 from the lift curve characteristic indicated by curve VL1 (high-speed characteristic) ;and, when the second rotation center axis line O 2 attains substantially the same height as that of the first rotation center axis line O 1 (when there is no vertical deviation), the valve characteristic substantially approximates the lift curve base characteristic.
- the valve characteristic approaches the lift curve characteristic (low-speed characteristic) represented by curve VL2 from the lift curve characteristic indicated by curve VL0.
- the valve 2 can always be driven with a characteristic appropriate for the engine operation state.
- this mechanism is provided with an eccentric position adjusting means (control member) 30 for rotating the control disc 14 having the eccentric section 15 so as to rotate the eccentric position of the eccentric section 15.
- the eccentric position adjusting mechanism 30 comprises an eccentricity control gear 31 formed around the outer periphery of the control disc 14, a gear shaft (control shaft) 32 having a control gear 35 in mesh with the eccentricity control gear 31, and an actuator 33 for driving the control shaft 32 to rotate; and controls operations via an ECU 34.
- detected information engine speed information
- detected information TPS information
- detected information AFS information
- airflow sensor not depicted
- the motor control in the eccentric position adjusting mechanism 30 is effected in response to the rotational speed and load state of the engine.
- the rotational phase of the control disc 14 is adjusted so as to attain a valve lift characteristic such as that of the curve VL1 in FIG. 8(c), thus yielding a long valve opening period.
- the rotational phase of the control disc 14 is adjusted so as to attain a valve lift characteristic such as that of the curve VL2 in FIG. 8(c), thus yielding a short valve opening period.
- the rotational state of the control disc 14 is adjusted so as to attain an intermediate valve lift characteristic between the curves VL1 and VL2 in FIG. 8(c).
- control gear 35 attached to the control shaft 32 is a scissors gear composed of two gears 35A and 35B, in which one gear 35A is secured to the control shaft 32, whereas the other gear 35B is rotatably attached to the control shaft 32.
- the gear 35B is disposed so as to abut to the gear 35A and is installed so as to receive a bias force toward the rotating direction from a torsion spring 38 disposed between the gear 35B and a journal 36 secured to the outer periphery of the control shaft 32, whereby the eccentricity control gear 31 on the control disc 14 side and the control gear 35 mesh with each other by means of both gears 35A and 35B without rattle.
- the gears 35A and 35B are caused to mesh with the eccentricity control gear 31 on the side of the control disc 14 around the outer periphery of the camshaft 11 that has already been installed. Then, the journal 36 is disposed at a predetermined axial position while being rotated with respect to the control shaft 32, thereby imparting bias forces to the gear 35B in axial and rotational directions. Thereafter, the journal 36 is fastened by a rotation-stopper pin 36A so as to be rotated together with the control shaft 32.
- each cylinder comprises a variable valve mechanism for driving an intake valve and a variable valve mechanism for driving an exhaust valve.
- an in-take-valve camshaft 11 IN and an exhaust-valve camshaft 11 EX are provided, and each of them comprises the cam lobe 12 and nonuniform coupling 13 for each cylinder.
- the eccentric position adjusting mechanism 30 comprises an eccentric control gear 31 on the control disc 14 side attached to the intake-valve camshaft 11 IN for each cylinder; an eccentric control gear 31 on the control disc 14 side attached to the exhaust-valve camshaft 11 EX for each cylinder; an intake-valve-side control shaft 32 adjacent to the intake-valve camshaft 11 IN ; an exhaust-valve-side control shaft 32 adjacent to the exhaust-valve camshaft 11 EX ; and a control gear 35, journal 36, and spring 38 attached to each control shaft 32 for each cylinder so as to mesh with each eccentricity control gear 31.
- only one actuator 33 is disposed at a non-depicted cylinder-head-side portion at an end part opposite to a sprocket (end member) 43.
- the actuator 33 is attached to an axial end portion of the exhaust-valve camshaft 11 EX .
- the actuator 33 is connected to an exhaust-valve-side drive gear mechanism 39A via a joint 33A.
- the driving force of the actuator 33 is transmitted from the exhaust-valve-side drive gear mechanism 39A to the exhaust-valve-side control shaft 32, whereby each eccentricity control gear 31 of the exhaust-valve camshaft 11 EX is driven to rotate.
- the exhaust-valve-side drive gear mechanism 39A is connected to an intake-valve-side drive gear mechanism 39B via an intermediate gear mechanism 40.
- the driving force of the actuator 33 is transmitted to the exhaust-valve-side control shaft 32 via the exhaust-valve-side drive gear mechanism 39A, intermediate gear mechanism 40, and intake-valve-side drive gear mechanism 39B, whereby each eccentricity control gear 31 of the intake-valve camshaft 11 IN is driven to rotate.
- each of the drive gear mechanisms 39A and 39B is constituted by a scissors gear 39e which is composed of two gears comprising a fixed gear 39b, secured to an axis 39a, and a movable gear 39d disposed with a spring 39c inserted between these gears; and a gear 39f secured to an end portion of the control shaft 32.
- the movable gear 39d is in mesh with the gear 39f together with the fixed gear 39b while being biased by the spring 39c toward the rotating direction, whereby no rattle occurs between the drive gear mechanisms 39A and 39B.
- the intermediate mechanism 40 comprises three gears 40a, 40b, and 40c which are in mesh with each other, and transmits the rotation of the axis 39a of the exhaust-valve-side drive gear mechanism 39A to the axis 39a of the intake-valve-side drive gear mechanism 39B in the same direction and at the same speed.
- each drive gear mechanism 39A, 39B is set to have the same number of teeth as those of each eccentricity control gear 31, while the gear 39f of each drive gear mechanism 39A, 39B is set to have the same number of teeth as those of each control gear 35, such that the actuator axis and the eccentricity control gear 31 have the same rotational angle.
- the actuator 33 comprises hydraulic-pressure supply means 51 including an oil control valve 50, and an actuator main body 52.
- the actuator main body 52 which is a so-called hydraulic actuator, rotates a vane 55 around its axis in a reciprocating fashion by means of hydraulic pressure.
- the actuator main body 52 comprises a housing 53, a shaft section (control shaft) 54 linked to the axis 39a of the exhaust-valve-side drive gear mechanism 39A via a joint mechanism (Oldham's joint), the vane 55 radially extending from the axis of the shaft section 54, and a first oil chamber 56A and a second oil chamber 56B which are partitioned by the vane 55.
- a spool valve 57 for the oil control valve 50.
- the spool valve 57 is biased by a compressed spring 58.
- the spool valve 57 is adjusted to a desired position against the bias force of the spring 58.
- the spool valve 57 is disposed between oil paths 60A and 60B respectively communicating with the first oil chamber 56A and second oil chamber 56B, a hydraulic oil inlet (oil inlet) 62 from an engine oil supply system 61, and drains 63A and 63B for discharging the hydraulic into the cylinder head 1.
- the vane 55 in response to the position of the spool valve 57, the vane 55 can be pivoted leftward or rightward and fixed.
- the position of the spool valve 57 can be adjusted by regulating the electromagnetic force of the coil section 59, i.e., by regulating electric power supplied to the coil section 59.
- a position sensor for detecting the position (rotational phase) of the vane 55 is provided. As shown in FIG. 2, as the ECU 34 performs feedback control according to the position of the vane 55 received from the position sensor, the electric power supplied to the coil section 59 is regulated so that the vane 55 is adjusted to a predetermined position.
- the rotational phase angle of the control disc 14, i.e., the rotation center (second rotation center axis line) O 2 of the engagement disc 16 is determined in response to the rotational phase angle of the vane 55.
- it is set such that the engagement disc 16 attains a low-speed eccentric state when the vane 55 is at the position most rotated to the right (indicated as phase angle 0° in the drawing), and a high-speed eccentric state when the vane 55 is at the position most rotated to the left (indicated as phase angle 180° in the drawing).
- the phase of the vane 55 is adjusted within the range from the low-speed eccentric position (vane phase angle of 0°) to the high-speed eccentric position (vane phase angle of 180°) in response to the engine rotational speed and the like.
- the sectional view of the housing 53 shown in FIG. 11 represents a state observed from the same direction as FIGS. 7 and 8 with respect to the camshaft 11.
- the engagement disc 16 also pivots clockwise in FIGS. 7 and 8. Namely, when the vane 55 is pivoted clockwise from the low-speed side to the high-speed side (i.e., in the direction in which the vane phase angle increases), the engagement disc 16 also pivots clockwise from the low-speed side to the high-speed side.
- This pivoting direction coincides with the rotating direction of the camshaft 11, thus allowing the engagement disc 16 to pivot from the low-speed side to the high-speed side with less load.
- the inner periphery of the eccentric section 15 slides against the outer periphery of the camshaft 11 via an oil film of a sliding bearing 47, whereas the outer periphery thereof slides against the inner periphery of the engagement disc 16 via a bearing 37.
- the eccentric section 15 is driven by the actuator 33 to rotate for phase adjustment, while it is assumed to be in a fixed state with respect to the engine rotation since it does not pivot relative thereto. Since the camshaft 11 and the engagement disc 16 pivot together with the engine rotation, the eccentric section 15 receives friction torque (dragging torque), in its rotating direction, from the camshaft 11 and engagement disc 16 at its sliding surfaces in the inner and outer peripheries.
- the eccentric section 15 when the eccentric section 15 is driven to rotate, it is influenced by this friction torque.
- the eccentric section 15 when the eccentric section 15 is driven to rotate in the direction along the friction torque, the eccentric section 15 can be rotated by a relatively small driving force as being backed up by the friction torque. Also, when the driving force applied to the eccentric section 15 is constant, the eccentric section 15 can be rapidly driven to rotate.
- variable valve mechanism either on the intake valve side see FIG. 1(A)! or on the exhaust valve side see FIG. 1(B)!, it is set such that, when the eccentric section 15 is pivoted from the low-speed side (referred to as first position) to the high-speed side (referred to as second position), the eccentric section 15 is driven to rotate in the direction along the friction torque as indicated by arrow nf, whereby the friction torque is utilized to rapidly pivot the eccentric section 15 from the low-speed side to the high-speed side.
- a turning force i.e., cam driving torque in response to the rotation of the crankshaft of the engine.
- Forces applied to the engagement disc 16 are a cam driving force T 1 as a turning force of the camshaft 11 from the camshaft-side slider 17, a reaction force F 1 from the cam-lobe-side slider 18 against the cam driving force T 1 , whereby a resultant force FF of the cam driving force T 1 , and reaction force F 1 is applied to the engagement disc 16.
- the resultant force FF acts in the direction perpendicular to the line connecting the center of the camshaft-side slider 17 and the center of the cam-lobe-side slider 18 but, opposite to that in FIG. 13, in the rotational direction for the cam-lobe-side slider 18. Also, the direction of such resultant force FF is reversed upon the maximum valve lifting.
- the force supporting the engagement disc 16 becomes a force against the resultant force FF, whereas the resultant force FF is generated by the cam driving torque. Accordingly, the cam driving torque acts in the reverse rotating direction for the cam-lobe-side slider 18 when the valve is operated to open, i.e., when the valve lift is rising, whereas it acts in the rotating direction for the cam-lobe-side slider 18 when the valve is operated to close.
- the vector of resultant force FF applied to the engagement disc 16 is represented in response to the phase of the cam 6 as shown in FIG. 14.
- the position of the cam-lobe-side slider 18 is indicated by C
- the camshaft-side slider 17 is indicated by S
- the engagement disc 16 is assumed to rotate counterclockwise.
- the upward direction of the ordinate indicates the position of the cam-lobe-side slider 18 with respect to the rotation center (first rotation center axis line) O 1 at the maximum valve lift
- the right side (clockwise direction) from the upward direction in the ordinate indicates the position of the cam-lobe-side slider 18 before the maximum valve lift
- the left side (counterclockwise direction) from the upward direction in the ordinate indicates the position of the cam-lobe-side slider 18 after the maximum valve lift.
- FL1 indicates the magnitude and direction of the resultant force FF applied to the engagement disc 16 when the valve is operated to open
- FL2 indicates the magnitude and direction of the resultant force FF applied to the engagement disc 16 when the valve is operated to close.
- the cam driving force T 1 is maximized when the upward cam driving torque reaches the maximum point after the valve is started to open, whereby the resultant force FF applied to the engagement disc 16 is also maximized.
- the resultant force FF at this time is orthogonal to the line connecting the camshaft-side slider 17 and cam-lobe-side slider 18, and acts in the reverse rotating direction for the cam-lobe-side slider 18. Namely, it shifts ahead of the phase of the camshaft-side slider 17 in the rotating direction by 90°, while shifting behind the phase of the cam-lobe-side slider 18 in the rotating direction by 90°.
- the cam driving force T 1 is maximized at the maximum point of downward cam driving torque before the valve begins to close, whereby the resultant force FF applied to the engagement disc 16 is also maximized.
- the resultant force FF at this time is orthogonal to the line connecting the camshaft-side slider 17 and cam-lobe-side slider 18 and aligns with the rotating direction for the cam-lobe-side slider 18. Namely, it shifts behind the phase of the camshaft-side slider 17 by 90° in the rotating direction, while shifting ahead of the phase of the cam-lobe-side slider 18 by 90° in the rotating direction.
- the two maximum loads applied to the engagement disc 16 are directed like letter V which is oriented opposite to the direction of the cam-lobe-side slider 18 at the maximum valve lift.
- the valve lift period is adjusted in response to the engine rotational speed and the like, so as to become shorter and longer respectively when the speed is lower and higher. Accordingly, assuming that the resultant force FF applied to the engagement disc 16 is represented by the characteristic view (vector chart) shown in FIG. 14, it can be illustrated as shown in FIGS. 15(A) and 15(B) for respective engine rotational speed regions.
- FIGS. 15(A) and 15(B) respectively show the cases of low-speed and high-speed engine rotations.
- the valve lift period is adjusted to become short, while the cam driving torque TL is mainly constituted by the valve spring force, whereby both upward cam driving torque maximum point and downward cam driving torque maximum point approach the maximum valve lift point.
- the maximum load direction of the resultant force FL1 at the time when the valve is operated to open approaches the rightward direction in abscissa (direction shifted clockwise by 90° from the phase angle of the cam-lobe-side slider 18 at the maximum valve lift); whereas, in response thereto, the maximum load direction of the resultant force FL2 at the time when the valve is operated to close approaches the leftward direction in abscissa (direction shifted counterclockwise by 90° from the phase angle of the cam-lobe-side slider 18 at the maximum valve lift).
- the valve lift period is adjusted to become longer, and the cam driving torque T H is mainly constituted by the inertia force of the valve, whereby both upward cam driving torque maximum point and downward cam driving torque maximum point move away from the maximum valve lift point.
- the maximum load direction of the resultant force FL1 at the time when the valve is operated to open moves away from the rightward direction in abscissa (direction shifted clockwise by 90° from the phase angle of the cam-lobe-side slider 18 at the maximum valve lift); whereas, in response thereto, the maximum load direction of the resultant force FL2 at the time when the valve is operated to close moves away from the leftward direction in abscissa (direction shifted counterclockwise by 90° from the phase angle of the cam-lobe-side slider 18 at the maximum valve lift).
- FIGS. 16 and 17 show cam driving torque required for driving a cam, i.e., cam driving torque to be applied to the engagement disc 16 via the camshaft 11, relative to the rotational angle of the camshaft.
- FIGS. 16 and 17 respectively show the cases where the engine rotates at low and high speeds. From these charts, it can be seen that, as the engine speed increases, the torque required for driving the cam increases, and the maximum torque point moves farther away from the maximum lift.
- one side face 16C of the engagement disc (internal rotating member) 16 opposes the arm section (attachment section) 20 of the cam lobe 12.
- the end face (flange section) 20A of the arm section 20 of the cam lobe 12 abuts to one side face of the engagement disc (internal rotating member) 16.
- both end faces 20A of the arm section 20 extends to a part which has a phase difference of about 90° or more with respect to the slider groove (second groove section) 16B formed in the engagement disc 16, and this extended portion is disposed outside the axis center as much as possible.
- One side face of the engagement disc 16 also abuts to thus extended arm section end face (flange section) 20A, whereby the engagement disc 16 abuts to the cam lobe 12 side, thus preventing the engagement disc 16 from tilting (falling) in the axis-swinging direction.
- a waved washer 46 attached to the rear end of the cam lobe 12 is a waved washer 46, by which the abutting force of the arm section end face 20A to the engagement disc 16 is enhanced, so as to secure a sufficient load for preventing the engagement disc 16 from falling.
- the engagement disc 16 and the cam lobe 12 rotate while generating a minute phase difference in response to their eccentricity, whereby the abutting portions of the engagement disc 16 and arm section end face 20A minutely slide against each other. Since lubricant oil (engine oil) is supplied thereto, these portions can slide smoothly.
- the above-mentioned bearing 37 is inserted between the sliding parts of the engagement disc 16 and eccentric section 15, i.e., between the outer periphery of the eccentric section 15 and inner periphery of the engagement disc 16.
- a needle bearing which can be inserted more compactly is used here, without being restricted thereto, various kinds of bearings can be employed as the bearing 37.
- the load on the starter and actuator upon starting or eccentric position adjustment can be reduced, whereby those having a low capacity and small size can be employed as the starter and actuator.
- a bearing such as needle bearing may be disposed between the sliding parts between the eccentric section 15 and camshaft 11, such that bearings are installed at both the sliding portion between the engagement disc 16 and eccentric section 15 and the sliding portion between the eccentric section 15 and camshaft 11.
- the system may increase its size and may lower its loading characteristic. If it matters, a bearing will be installed at one of the sliding portions.
- the bearing is preferably inserted between the engagement disc 16 and eccentric section 15, having a diameter greater than that of the camshaft 11 and eccentric section 15, since a bearing property can be exhibited more effectively.
- Numerals 7E, 11A, and 11B in FIG. 3 refer to oil holes for supplying lubricant oil (engine oil) to the respective sliding portions.
- variable valve mechanism in accordance with the first embodiment of the present invention is configured as mentioned above; in the internal combustion engine equipped with such a variable valve mechanism, the valve opening characteristic is controlled while the rotational phase of the control disc 14 is adjusted via the eccentric position adjusting mechanism 30.
- the rotational phase of the control disc 14 corresponding to the rotational speed and load state of the engine is set, and the control disc 14 is driven via the operation control of the actuator 33 such that the actual rotational phase of the control disc 14 attains thus set state according to the detection signal of the position sensor.
- the eccentric section 15 is pivoted so as to adjust the phase angle such that, while the rotation center (second rotation center axis line) O 2 of the engagement disc 16 is displaced, the phase angle characteristic approaches the curve VL1 in FIG. 8 as the rotational speed and load of the engine increase, for example, thereby elongating the valve opening period, whereas it approaches the curve VL2 in FIG. 8 as the rotational speed and load of the engine decrease, thereby shortening the valve opening period.
- the valve can be driven optimally for the engine operation state.
- the valve lift characteristic can be adjusted continuously, the valve can always be driven with a characteristic optimal for the engine operation state.
- variable valve mechanism either on the intake valve side see FIG. 1(A)! or on the exhaust valve side see FIG. 1(B)!, when the eccentric section 15 pivots from the low-speed side to the high-speed side, the eccentric section 15 is driven to rotate in the direction along the friction torque (dragging torque), whereby the eccentric section 15 can be rapidly pivoted from the low-speed side to high speed side of the eccentric section 15 by use of the friction torque.
- the response for changing the low-speed side to high-speed side of the valve timing is sped up, whereby the optimal timing corresponding to the rotational speed (corresponding to the vehicle speed) can be rapidly achieved upon acceleration as well, thus contributing to improvement in acceleration performances such as improvement in acceleration feeling. It is also advantageous in that such an excellent acceleration response can be realized by the actuator 33 having a relatively small capacity without increasing the capacity thereof.
- the scissors gear (control gear) 35 is incorporated in the control shaft 32 in view of the space of each cylinder; at the camshaft end portion on the actuator 33 side, in order to prevent backlash from occurring with respect to the intermediate gear mechanism 40, the scissors gear 39e is installed in the gears not on the control shaft 32 side but on the camshaft 11 side.
- Such setting takes account of the characteristic that a vehicle engine is typically equipped with a transmission, whereby, upon acceleration of the vehicle, the engine speed drastically decreases together with up-shifting.
- FIG. 19 which shows the result of investigation concerning a changing characteristic of engine speed when the transmission is successively upshifted from the first speed to second and third speeds
- the descending rate of engine speed upon upshifting is three times as much as the ascending rate of the engine speed with no shift change in the case of upshifting from the first to second speed in which their difference is the smallest, and becomes greater upon up-shifting from the second to third speed. Accordingly, it can be seen that the engine speed drastically decreases upon upshifting.
- the eccentric section 15 be pivoted from the high-speed side to the low-speed side without failing to catch up with the drastic decrease in engine speed caused by upshifting, so that the valve timing is changed from the high-speed side to the low-seed side more rapidly. Therefore, the friction torque is utilized to pivot the eccentric section 15 from the high-speed side to the low-speed side, thus allowing the valve timing to be changed rapidly.
- variable valve mechanism in accordance with the second embodiment of the present invention is configured as mentioned above; in the internal combustion engine equipped with such variable valve mechanism, either on the intake valve side or exhaust valve side, as shown in FIGS. 18(A) and 18(B), when the eccentric section 15 is pivoted from the high-speed side to the low-speed side, the eccentric section 15 is driven to rotate in the direction along the friction torque (dragging torque), whereby the eccentric section 15 can be rapidly pivoted from the high-speed side to the low-speed side by use of the friction torque.
- the eccentric section 15 can be pivoted from the high-speed side to the low-speed side, whereby the valve timing can be rapidly changed from the high-speed side to the low-speed side. Accordingly, in the automobile engine, when the vehicle speed increases (upon acceleration), the optimal valve timing corresponding to the engine rotational speed can be rapidly attained even upon upshifting, thus contributing to improvement in acceleration performances such as improvement in acceleration feeling. It is also advantageous in that such an excellent acceleration response can be realized by the actuator 33 having a relatively small capacity without increasing the capacity thereof.
- This embodiment is set such that, though each constituent of the mechanism is similar to that in the first embodiment, as shown in FIGS. 20(A) and 20(B), when the eccentric section 15 is pivoted from the low-speed side to the high-speed side, the eccentric section 15 on the exhaust side see FIG. 20(A)! is driven to rotate in the direction nf along the friction torque (dragging torque), whereas the eccentric section 15 on the intake side see FIG. 20(B)! is driven to rotate in the direction nf opposite to the friction torque (dragging torque).
- the respective eccentric position adjusting mechanisms 30, 30 on the exhaust valve side and intake valve side are driven by the single actuator 33.
- variable valve mechanism in accordance with the third embodiment of the present invention is configured as mentioned above; when the eccentric section 15 is pivoted from the low-speed side (first position) to the high-speed side (second position), the eccentric section 15 on the exhaust valve side is driven to rotate in the direction nf along the friction torque (dragging torque), whereby the driving load becomes smaller as being backed up by the friction torque, whereas the eccentric section 15 on the intake valve side is driven to rotate in the direction nf opposite to the friction torque (dragging torque), whereby the driving torque becomes greater as being resisted by the friction torque.
- the eccentric section 15 on the exhaust valve side is driven to rotate in the direction ns opposite to the friction torque (dragging torque), thereby yielding a larger driving load as being resisted by the friction torque, whereas the eccentric section 15 on the intake valve side is driven to rotate in the direction ns along the friction torque (dragging torque), thereby yielding a smaller driving load as being backed up by the friction torque.
- the actuator 33 when the eccentric section 15 is pivoted from the low-speed side to the high-speed side, the resistance (i.e., increase in load) effected by friction torque on the intake valve side is canceled by the backup (i.e., decrease in load) effected by the friction torque on the exhaust valve side, whereby the actuator 33, as a whole (when the exhaust valve side and intake valve side are collectively taken into account), is hardly influenced by such friction torque.
- valve timing control can be set easily.
- the respective eccentric position adjusting mechanisms 30, 30 are driven by the single actuator 33.
- variable valve mechanism in accordance with the fourth embodiment of the present invention is configured as mentioned above, as with the third embodiment, when the eccentric section 15 is pivoted from the low-speed side to the high-speed side or from the high-speed side to the low-spee dside, the resistance (i.e., increase in load) effected by the friction torque on one of the exhaust valve side and intake valve side is canceled by the backup (i.e., decrease in load) effected by the friction torque on the other side, whereby the actuator 33, as a whole (when the exhaust valve side and intake valve side are collectively taken into account), is hardly influenced by such friction torque.
- exhaust valve side and intake valve side are driven by the single actuator in each embodiment, they may be driven separately as well. Also, the configuration in accordance with each embodiment may be partly applied to one of the exhaust valve side and intake valve side as well.
- variable valve mechanism of each embodiment is also applicable to each variable valve mechanism referred to in the column of Background Art with its corresponding publication number.
- the axis centers of the first pin element and second pin element are shifted by about 180° from each other around the first rotation center axis line O 1 so that the axis center of the first pin element, first rotation center axis line O 1 , and the axis center of the second pin element substantially align with each other in the variable valve mechanism of each embodiment; the relative positional relationship between the axis center of the first pin element, first rotation center axis line O 1 , and the axis center of the second pin element is not restricted thereto, namely, the axis center of the first pin element, first rotation center axis line O 1 , and the axis center of the second pin element may be disposed with an angle other than 180° (e.g., either an obtuse or acute angle).
- the mechanism of the present invention can be applied to all the types of engines including various type of straight multi-cylinder engines such as four-cylinder engines.
- variable valve mechanism of this invention is also applicable to various kinds of the valve driving forms described as Background Art.
Abstract
Description
Claims (10)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP02563397A JP3899576B2 (en) | 1997-02-07 | 1997-02-07 | Variable valve mechanism and internal combustion engine with variable valve mechanism |
JP9-025633 | 1997-02-07 |
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US5931128A true US5931128A (en) | 1999-08-03 |
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US09/010,623 Expired - Lifetime US5931128A (en) | 1997-02-07 | 1998-01-22 | Variable valve mechanism and internal combustion engine with the same |
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US (1) | US5931128A (en) |
JP (1) | JP3899576B2 (en) |
KR (1) | KR100286513B1 (en) |
DE (1) | DE19804575B4 (en) |
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US6343578B1 (en) * | 1999-09-08 | 2002-02-05 | Dr. Ing. H.C.F. Porsche Ag | Device and method for variable valve timing in an internal combustion engine |
EP1285158A1 (en) * | 2000-05-30 | 2003-02-26 | Bishop Innovation Limited | Variable timing mechanism for a rotary valve |
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US6886532B2 (en) * | 2001-03-13 | 2005-05-03 | Nissan Motor Co., Ltd. | Intake system of internal combustion engine |
US20050235934A1 (en) * | 2004-04-27 | 2005-10-27 | Matthias Becker | Variable mechanical valve timing mechanism having an adjusting device |
US20080017150A1 (en) * | 2004-09-15 | 2008-01-24 | Yamaha Hatsudoki Kabushiki Kaisha | Variable Valve Drive Device, Engine, and Motorcycle |
US20090031973A1 (en) * | 2007-07-30 | 2009-02-05 | Mitsubishi Jidosha Kogyo Kabushiki Kaisha | Engine equipped with adjustable valve timing mechanism |
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US8935076B2 (en) * | 2009-03-30 | 2015-01-13 | Toyota Jidosha Kabushiki Kaisha | Controller for internal combustion engine |
US20120016565A1 (en) * | 2009-03-30 | 2012-01-19 | Fujitsu Ten Limited | Controller for internal combustion engine |
CN103003533A (en) * | 2010-07-09 | 2013-03-27 | 戴姆勒股份公司 | Camshaft adjuster for a motor vehicle |
CN104870761A (en) * | 2012-12-25 | 2015-08-26 | 丰田自动车株式会社 | Variable valve device |
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US10634067B2 (en) | 2015-12-11 | 2020-04-28 | Hyundai Motor Company | System and method for controlling valve timing of continuous variable valve duration engine |
US10920679B2 (en) | 2015-12-11 | 2021-02-16 | Hyundai Motor Company | Method for controlling of valve timing of continuous variable valve duration engine |
US20180100444A1 (en) * | 2016-03-16 | 2018-04-12 | Hyundai Motor Company | System and method for controlling valve timing of continuous variable valve duration engine |
US10634066B2 (en) * | 2016-03-16 | 2020-04-28 | Hyundai Motor Company | System and method for controlling valve timing of continuous variable valve duration engine |
CN114542245A (en) * | 2022-01-24 | 2022-05-27 | 安徽理工大学 | Motor vehicle tail gas degradation treatment equipment |
CN114542245B (en) * | 2022-01-24 | 2023-05-02 | 安徽理工大学 | Motor vehicle tail gas degradation treatment equipment |
Also Published As
Publication number | Publication date |
---|---|
DE19804575A1 (en) | 1998-09-03 |
JPH10220209A (en) | 1998-08-18 |
DE19804575B4 (en) | 2008-04-10 |
JP3899576B2 (en) | 2007-03-28 |
KR19980071049A (en) | 1998-10-26 |
KR100286513B1 (en) | 2001-04-16 |
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